Hepatocellular carcinoma (HCC) is a major public health problem with few effective treatment options. In an effort to develop new treatment modalities, we have identified a class of small molecule agents that disrupt the beat-catenin pathway, one of the major signaling pathways in many, if not most, HCC tumors. The wnt (wingless and int-1)/b-catenin signaling pathway is critical for vertebrate development but is also aberrantly activated in a number of tumor types including HCC. Wnt/b-catenin signaling integrates cell-adhesion and motility signals with growth, proliferation and survival. In molecular terms, beta-catenin is a transcriptional regulator that interacts with a number of co-repressors and co-activators to regulate the transcription of target genes. In HCC mutations in b-catenin itself or in genes encoding proteins that regulate beta-catenin stability lead to elevated levels of nuclear b-catenin and transcriptional activation of cellular proliferation and survival programs. New agents that target specific aspects of beta-catenin signaling present the opportunity to target HCC tumors in a selective and efficacious manner. The goal of the research proposed in this application is to validate a new class of compounds directed against the wnt-b-catenin pathway using in vitro (cell-based) and in vivo (mouse xenograft) studies. In the first Specific Aim, 544 analogues of our current lead compound will be tested in our HepG2 cell-based assay. In Aim 2, a panel of human cancer cell lines will be examined for sensitivity to a five best b-catenin inhibitors. Sensitive cell lines and active compounds will be selected for evaluation using in vivo models of HCC. The inhibitors will be tested for in vivo toxicity as well as pharmacokinetic properties in mice in the third Specific Aim. Finally, in the fourth Specific Aim, sensitive cell lines will be used in mouse xenograft models using optimized dose and route of administration of active compounds to demonstrate in vivo efficacy. Together these studies will validate beta-catenin inhibitors as anti- HCC pre-clinical candidates. The long-term goal of this research is to move this class of compounds into human clinical trials. PUBLIC HEALTH RELEVANCE: Liver cancer is a major cause of death throughout the world. There are very few effective treatments for liver cancer and consequently, the prognosis for patients with this disease is poor. The research outlined here will evaluate a group of compounds that block a key pathway involved in liver cancer as potential anticancer drugs. If successful, these studies will provide a new therapeutic option for the treatment of liver cancer.